Rag or bandana tweekers carry around to wipe their quag. (The lighter leaves a black residue on the outside of the glass pipe so tweekers wipe the residue off with a rag or a "quag rag")
Man 1:Look, that guy over there is a tweeker
Man 2:How do you know?
Man 1:I see his quag rag hanging out his back pocket
A bloody rag originates from when women wore a rag, similar to a cloth diaper, with strings to tie it around their waste, during that bloody time of the month. The most modern form would be a maxi-pad, but not a tampon, even though some refer to tampons as rags.
She threw that bloody rag in the toilet, and expected it to flush? Where's my plunger, the dumb bitch!